Mathematical Simulation and Validation of a Wastewater Treatment Plant in Northern Italy

The aim of this study was to calibrate and validate activated sludge model No. 3 (ASM3) for an Italian municipal wastewater treatment plant (WWTP) located in Friuli Venezia Giulia region. The model was modified and calibrated using experimental data from aerobic and anoxic respirometric batch tests with activated sludge from the biological treatment line of the studied WWTP. Calibrated set of model's kinetic parameters and stoichiometric coefficients, obtained from these tests, were able to describe the oxygen uptake rate as well the ammonia and nitrate uptake rate of the activated sludge. The model was validated using full-scale operating data from the biological unit of the WWTP. Validated ASM3 allowed successfull simulation and prediction of chemical oxygen demand decay, nitriication and denitrification processes, oxygen consumption, and sludge production. Finally, sensitivity analysis with respect to model outputs was performed and accuracy of the model determined by evaluating the theoretical predictions using the root mean squared error (0.2-72%) and the Nash and Sutcliff efficiency index values (0.806-0.999). The validated ASM3 could be used as a decision tool, predicting the real operating conditions under which best efficiency of the WWTP with low sludge production may be expected.